An Essay Concerning Humane Understanding, Volume 2: MDCXC, Based on the 2nd Edition, Books 3 and 4
John Locke · en
is a part of his body, as that it is less than his body. And he that can
doubt whether it be less, will as certainly doubt whether it be a part.
So that the maxim, the whole is bigger than a part, can never be made
use of to prove the little finger less than the body, but when it is
useless, by being brought to convince one of a truth which he knows
already. For he that does not certainly know that any parcel of matter,
with another parcel of matter joined to it, is bigger than either of
them alone, will never be able to know it by the help of these two
relative terms, whole and part, make of them what maxim you please.
4. Dangerous to build upon precarious Principles.
But be it in the mathematics as it will, whether it be clearer, that,
taking an inch from a black line of two inches, and an inch from a red
line of two inches, the remaining parts of the two lines will be equal,
or that IF YOU TAKE EQUALS FROM EQUALS, THE REMAINDER WILL BE EQUALS:
which, I say, of these two is the clearer and first known, I leave to
any one to determine, it not being material to my present occasion. That
which I have here to do, is to inquire, whether, if it be the readiest
way to knowledge to begin with general maxims, and build upon them, it
be yet a safe way to take the PRINCIPLES which are laid down in any
other science as unquestionable truths; and so receive them without
examination, and adhere to them, without suffering them to be doubted
of, because mathematicians have been so happy, or so fair, to use none
but self-evident and undeniable. If this be so, I know not what may not
pass for truth in morality, what may not be introduced and proved in
natural philosophy.